Real-time Control Algorithm Research Articles

Remote Laboratory for Advanced Motion Control Experiments

Lately, a number of remote laboratories for motion control has been developed worldwide as a valuable tool for teaching mechatronics students basic control strategies. However, there is a lack of remote laboratories that can be used in teaching advanced motion control. In this paper a remote laboratory for advanced motion control developed at the University of South Australia is described. The real time control algorithms, including H-infinity control, are successfully implemented in an FPGA environment. This paper also gives a detailed description of the graphical user interface developed for this laboratory, which enables effective remote experimentation.

Real-Time Trajectory Control of Robots Omnidirectional Mobile Obstacle Avoidance

On the basis of Dick Stella algorithm and Bessel Curve, this paper proposes an improved algorithm for real-time obstacle avoidance control of mobile robots. With strong robustness, this algorithm can effectively solve the problem of robot path planning and tracking while meeting the dynamic constraint conditions. The simulation results show that the improved algorithm shortens the robot moving period and remarkably improves the motion planning in robot obstacle avoidance.

A Feed-Forward Approach for the Real-Time Estimation and Control of MFB50 and SOI In Diesel Engines

Feed-forward low-throughput models have been developed to predict MFB50 and to control SOI in order to achieve a specific MFB50 target for diesel engines. The models have been assessed on a GMPT-E Euro 5 diesel engine, installed at the dynamic test bench at ICEAL-PT (Internal Combustion Engine Advanced Laboratory at the Politecnico di Torino) and applied to both steady state and transient engine operating conditions. MFB50 indicates the crank angle at which 50% of the fuel mass fraction has burned, and is currently used extensively in control algorithms to optimize combustion phasing in diesel engines in real-time. MFB50 is generally used in closed-loop combustion control applications, where it is calculated by the engine control unit, cycle-by-cycle and cylinder by-cylinder, on the basis of the measured in-cylinder pressure trace, and is adjusted in order to reduce the fuel consumption, combustion noise and engine-out emissions. A feed-forward approach has been developed in this paper. This approach is capable of predicting MFB50 on the basis of several parameters, such as, the in-chamber thermodynamic conditions, the injected fuel quantities and timings, the injection pressure, the oxygen concentration and the engine speed and load. The approach has also been inverted in order to predict the start of injection required to achieve a specific MFB50 target in real time. This method can be used in model-based real-time control algorithms to adjust the engine parameters in order to prevent the occurrence of nonoptimal combustion cycles.

Model Predictive Control of Swarms of Spacecraft Using Sequential Convex Programming

This paper presents a decentralized, model predictive control algorithm for the optimal guidance and reconfiguration of swarms of spacecraft composed of hundreds to thousands of agents with limited capabilities. In previous work, -invariant orbits have been found to provide collision-free motion for hundreds of orbits in a low Earth orbit. This paper develops real-time optimal control algorithms for the swarm reconfiguration that involve transferring from one -invariant orbit to another while avoiding collisions and minimizing fuel. The proposed model predictive control-sequential convex programming algorithm uses sequential convex programming to solve a series of approximate path planning problems until the solution converges. By updating the optimal trajectories during the reconfiguration, the model predictive control algorithm results in decentralized computations and communication between neighboring spacecraft only. Additionally, model predictive control reduces the horizon of the convex optimizations, which reduces the run time of the algorithm. Multiple time steps, time-varying collision constraints, and communication requirements are developed to guarantee stability, feasibility, and robustness of the model predictive control-sequential convex programming algorithm.

Optimizing the compounding process of hydrocarbon mixtures

This article proposing the dynamic model for evaluating the properties of additive mixtures with nonlinear interactions between components. The model-based algorithms improved planning process mixing in the flow lines in filling fuels with different characteristics, optimal control algorithms mixing in the lines filling in real-time control algorithms and filling the fuel tank. The operability of appropriated algorithms is tested by the optimization task for technology flow control for diesel fuel compounding on the flow.

A direct non-buffer rate control algorithm for real time video compression

Rate control (RC) is crucial in controlling compression bitrates and encoding qualities for networked video applications. In this paper, we propose a direct non-buffer real-time rate control algorithm for video encoding, which has two unique features. First, unlike traditional algorithms which adopt buffers in rate control, the proposed algorithm does not use a buffer in rate regulation which can reduce the delay and improve real-time response. Second, we propose a new Proportional-Integral-Derivative (PID) bit controller to directly control encoding bitrates. In addition, we also develop a simple but effective method for real-time target bit allocation. To the best of our knowledge, this is the first work that conducts video rate control without using a buffer. Our extensive experimental results have demonstrated that the proposed algorithm outperforms the MPEG-4 rate control algorithm by achieving more accurate rate regulation and improving overall coding quality.

Model Predictive Control for Real-Time Tumor Motion Compensation in Adaptive Radiotherapy

This paper presents the development and real-time implementation of a control system to automatically adjust the patient support system (PSS) position, thereby compensating for tumor motion caused by respiration and patient movements during radiotherapy treatment. The control scheme utilizes an observer to estimate the PSS state feedback, and a tumor position prediction algorithm to provide the reference for a model predictive controller. The real-time control algorithm was implemented using the Matlab and Simulink environments, with the communication with the clinical PSS performed through the dSPACE real-time system. The controller was shown to be able to position the PSS accurately and was able to track and compensate for organ motion with an accuracy of less than 1 mm in terms of root mean square error, giving rise to dose distributions indistinguishable from a static beam on a fixed target. From a clinical perspective, the increased targeting accuracy will enable an increased dose to the tumor without compromising the surrounding healthy tissues.

A real-time and closed-loop control algorithm for cascaded multilevel inverter based on artificial neural network.

In order to control the cascaded H-bridges (CHB) converter with staircase modulation strategy in a real-time manner, a real-time and closed-loop control algorithm based on artificial neural network (ANN) for three-phase CHB converter is proposed in this paper. It costs little computation time and memory. It has two steps. In the first step, hierarchical particle swarm optimizer with time-varying acceleration coefficient (HPSO-TVAC) algorithm is employed to minimize the total harmonic distortion (THD) and generate the optimal switching angles offline. In the second step, part of optimal switching angles are used to train an ANN and the well-designed ANN can generate optimal switching angles in a real-time manner. Compared with previous real-time algorithm, the proposed algorithm is suitable for a wider range of modulation index and results in a smaller THD and a lower calculation time. Furthermore, the well-designed ANN is embedded into a closed-loop control algorithm for CHB converter with variable direct voltage (DC) sources. Simulation results demonstrate that the proposed closed-loop control algorithm is able to quickly stabilize load voltage and minimize the line current's THD (<5%) when subjecting the DC sources disturbance or load disturbance. In real design stage, a switching angle pulse generation scheme is proposed and experiment results verify its correctness.

Separable Model Predictive Control via Alternating Direction Method of Multipliers for Large-scale Systems

In this paper, an alternating direction method of multipliers (ADMM) based real-time model predictive control (MPC) algorithm is presented. With the use of indicator function and by introducing extra consensus constraints, the constrained MPC problem can be formulated as a separable MPC problem, which can be computed very efficiently by projected gradient descent ADMM update steps and Riccati recursions. The sequence of the objective value of this constrained real-time ADMM-type MPC algorithm satisfies a linear convergence rate. The procedure is also extended to distributed systems with constraints, in which the variables of each subsystems communicate with their neighbors and update in the Gauss-Seidel way. An illustrative example shows the effectiveness of this approach.

航空機の突風回避飛行に対する実時間最適制御

An onboard real-time optimal control method is applied to the guidance of an aircraft in the interest of balancing safe and efficient flight. The aircraft, which has a laser LIDAR (LIght Detection And Ranging) system to detect turbulence in the forward region, is given the real-time optimal control to avoid the region. The real-time optimal control algorithm in this study is based on Receding Horizon control method with Neighboring Extremal method. The Neighboring Extremal method, which solves the change in the optimal solution into the variation of the problem definition, can be applied only in the case that the variation is very small, and it is difficult to efficiently deal with inequality constraint conditions in the problem. This paper aims to resolve these issues. To confirm the effectiveness of the proposed algorithm, the avoidance flight from the turbulence that the aircraft encounters is numerically simulated, and satisfactory results are obtained.

Design and Development of Control System for Three Phase Induction Motor using PIC Microcontroller

The paper deals with the design of control system for improving efficiency of three phase induction motor. The advantage of this system is that it reduces the power consumption and improves the efficacy of an induction motor. The SPWM technique is used in this system for the purpose of qualitative development. It is a special type of pulse width modulation, in which the width of the pulses varies and as a result of which the speed of an induction motor changes. The number of the pulses per half cycle changes by applying an interrupt signal to microcontroller, which gives better results in comparison to the previous one. This is the digital technique for three phase inverter using single phase supply. The system becomes flexible by using microcontroller. It is possible to change the real-time control algorithms without change in hardware. It will reduce an overall cost. It has a small size of control circuit for the three phase inverter. Simulation is carried out using PROTEUS and a prototype model is built in the experimental design for verification of simulation results. PIC microcontroller is used to generate PWM pulses and also take the decision for generating number of pulses by giving the interrupt to the microcontroller.

Development of a microcontroller-based system with hardware-in-the-loop method for real-time control algorithms prototyping

It is well known that the hardware-in-the-loop simulation (HILS) is a wide range used method for control prototyping and system modeling applications. This paper presents a microcontroller-based control system design and development for real-time control algorithms prototyping using the HILS strategy. The entire hardware module of this system is based on a BigPIC6 development board interfaced to the Matlab/Simulink software environment. The plant is modeled by using Simulink components on the xPC target and the control algorithms are implemented on the microcontroller-based module. As a result of the adopted development strategy, a powerful and versatile system has been obtained for real-time control algorithms prototyping and development. A large set of experimental results proves the feasibility and efficiency of the developed HILS system, providing a very efficient research and development tool both for modeling and experimental purposes. Index Terms — hardware-in-the-loop, microcontroller, real-time control, rapid prototyping, HIL simulation

Development of real-time plasma analysis and control algorithms for the TCV tokamak using Simulink

One of the key features of the new digital plasma control system installed on the TCV tokamak is the possibility to rapidly design, test and deploy real-time algorithms. With this flexibility the new control system has been used for a large number of new experiments which exploit TCV's powerful actuators consisting of 16 individually controllable poloidal field coils and 7 real-time steerable electron cyclotron (EC) launchers. The system has been used for various applications, ranging from event-based real-time MHD control to real-time current diffusion simulations. These advances have propelled real-time control to one of the cornerstones of the TCV experimental program. Use of the Simulink graphical programming language to directly program the control system has greatly facilitated algorithm development and allowed a multitude of different algorithms to be deployed in a short time. This paper will give an overview of the developed algorithms and their application in physics experiments.

Real-time voltage control algorithm with switched capacitors in smart distribution system in presence of renewable generations

One of the most important responsibilities of Distribution System Operator (DSO) is to maintain the customer voltage within specified ranges. Capacitor banks have long been used to provide voltage support and to correct displacement power factor on distribution network. This paper presents a new approach for real time voltage control of distribution networks that has improvements over the conventional voltage control models. This approach will be active in emergency conditions where, in real time, the voltages in some nodes leave their permissible ranges. In the proposed model, it is assumed that renewable distributed generations are integrated in the distribution system, and the communication infrastructure of smart grid has already been implemented. Also, all the capacitors are fitted with Remote Terminal Unit (RTU) and are completely accessible and controllable. Unlike previous voltage control methods, the proposed approach does not need the load and renewable generation forecast data to regulate voltage. Moreover, the calculation time of the proposed approach is considerably reduced. The proposed voltage control algorithm is applied on two different models, and each presented model has a substantial improvement over previous models. DSO can choose one of them based on a trade-off between cost and power quality index. To verify the effectiveness and robustness of the proposed control scheme, the developed voltage control scheme is tested on a typical distribution network. The simulation results show that the proposed real time voltage control has the capability to maintain distribution voltage in specified ranges.

A new algorithm for real-time pressure control in water distribution networks

This paper presents a new logic algorithm for real-time control of regulation valves in water distribution networks. This method entails identifying in real time the appropriate closure setting of regulation valves in order to reach and keep the desired piezometric height at the control node(s), by making use of measurements concerning both the piezometric height at the control node(s) and the water discharge in the pipes fitted with regulation valves. In the numerical application herein described this control algorithm is implemented within a hydraulic simulation model and is tested in the case study of a real distribution network, in which there is only one control valve, installed in the pipe linking the serving tank to the network. Results showed excellent performance in terms of pressure regulation (with very small deviations from the desired set-point value) and leakage reduction under various operation conditions.

The Design of the Anti-Rolling Tank Control System Based on CAN-Bus

As the anti-rolling tank controller based on PLC is unable to fulfill the high strength of calculation of the automatic real-time control algorithm, which leads to the limitation of anti-rolling effect, this paper proposes a distributed embedded controller based on CAN bus communication. The controller uses a high-performance ARM chip as the main chip to meet the complex algorithm calculation requirements. For CAN bus communication between the distributed modules, the system is simple and reliable. Distributed embedded controller consists of the center controller, the IO controller and the communication adapter whose hardware design and software design are proposed in this paper, and achieves the acquisition of real-time data of ships status information and intelligent control algorithm. Through simulation and bench simulation experiments, the controller can achieves the excellent anti-rolling effect. The distributed controller architecture is simple and easy to expand and spread to various tonnages of real ships.

A Multiaxis Programmable Robot for the Study of Multibody Spine Biomechanics Using a Real-Time Trajectory Path Modification Force and Displacement Control Strategy

Robotic testing offers potential advantages over conventional methods including coordinated control of multiple degrees of freedom (DOF) and enhanced fidelity that to date have not been fully utilized. Previous robotic efforts in spine biomechanics have largely been limited to pure displacement control methods and slow quasi-static hybrid control approaches incorporating only one motion segment unit (MSU). The ability to program and selectively direct single or multibody spinal end loads in real-time would represent a significant step forward in the application of robotic testing methods. The current paper describes the development of a custom programmable robotic testing system and application of a novel force control algorithm. A custom robotic testing system with a single 4 DOF serial manipulator was fabricated and assembled. Feedback via position encoders and a six-axis load sensor were established to develop, program, and evaluate control capabilities. A calibration correction scheme was employed to account for changes in load sensor orientation and determination of spinal loads. A real-time force control algorithm was implemented that employed a real-time trajectory path modification feature of the controller. Pilot tests applied 3 Nm pure bending moments to a human cadaveric C2–T1 specimen in flexion and extension to assess the ability to control spinal end loads, and to compare the resulting motion response to previously published data. Stable accurate position control was achieved to within ±2 times the encoder resolution for each axis. Stable control of spinal end body forces was maintained to within a maximum error of 6.3 N in flexion. Sagittal flexibility data recorded from rostral and caudally placed six-axis load sensors were in good agreement, indicating a pure moment loading condition. Individual MSU rotations were consistent with previously reported data from nonrobotic protocols. The force control algorithm required 5–10 path iterations before converging to programmed end body forces within a targeted tolerance. Commercially available components were integrated to create a fully programmable custom 4 DOF gantry robot. Individual actuator performance was assessed. A real-time force control algorithm based on trajectory path modification was developed and implemented. Within a reasonable number of programmed path iterations, good control of spinal end body forces and moments, as well as a motion response consistent with previous reported data, were obtained throughout a full physiologic flexion-extension range of motion in the human subaxial cervical spine.

Quasi-linear analytical approach to stick-slip friction in the frequency domain

SUMMARY A quasi-linear analytical approach to the Karnopp nonlinear model of stick–slip friction is presented. The proposed linear description has additional phase lag at low frequencies in comparison with the well-known describing function of the Coulomb friction model. The new approach is appropriate to describe stick–slip friction behavior in the frequency domain and to predict limit cycling. The minimal critical frequency to stop the sticking is given. The reliability of the quasi-linear approach was experimentally verified by the common sine-scan frequency response technique. The analytical form of the stick–slip description allows for rapid computation and can therefore be of use in real-time control algorithms. Copyright © 2013 John Wiley & Sons, Ltd.

Cumulative Travel-Time Responsive Real-Time Intersection Control Algorithm in the Connected Vehicle Environment

This paper presents a cumulative travel-time responsive (CTR) real-time intersection control algorithm that takes full advantage of connected vehicles (CVs). The potential benefits of the proposed CTR algorithm under varying imperfect CV market penetration rates and traffic congestion conditions were investigated. The core of the CTR algorithm is based on a stochastic state estimation technique utilizing Kalman filtering that is used in estimating the cumulative travel times under imperfect market penetration rates at every update interval. Comprehensive simulation experiments covering varying volume-to-capacity ratios and imperfect market penetration rates were performed at a hypothetical isolated intersection with two through lanes and a single left-turn lane at each approach. At 100% market penetration, the CTR algorithm improved the total delay time and average speed of the intersection by 34 and 36%, respectively, compared to an optimized actuated control. It was found that at least 30% market penetration rates are needed to realize the benefits of the CTR algorithm.

Digital Detection, Control, and Distribution System for Co-Phase Traction Power Supply Application

Unbalance and reactive power currents of electric railway will result in poor power quality of three-phase industrial power grid. A co-phase traction power supply system is introduced in this paper to solve these problems by adopting single-phase ac-dc-ac converter. The converter is connected between two secondary windings of traction transformer with abilities of active power transmission and reactive power compensation. Because of the power conversion, the co-phase supply system can utilize single-phase feeding connection scheme instead of traditional two-phase feeding scheme. An actual 10 MVA/27.5 kV co-phase system with impedance-matching balance transformer is designed, developed, and tested. Its real-time detection, control, and distribution algorithms with field programmable gate array-based implementation are introduced. Some test running results validate the performance of the digital controller and demonstrate the feasibility of the proposed co-phase power supply system.